U.S. patent application number 15/606041 was filed with the patent office on 2018-04-12 for underwater mobile body.
This patent application is currently assigned to FUJI XEROX CO., LTD.. The applicant listed for this patent is FUJI XEROX CO., LTD.. Invention is credited to Motofumi BABA, Tsutomu KIMURA, Yoshihiko NEMOTO, Masahiro SATO, Kengo TOKUCHI, Akihito YAMAUCHI.
Application Number | 20180099573 15/606041 |
Document ID | / |
Family ID | 61830612 |
Filed Date | 2018-04-12 |
United States Patent
Application |
20180099573 |
Kind Code |
A1 |
NEMOTO; Yoshihiko ; et
al. |
April 12, 2018 |
UNDERWATER MOBILE BODY
Abstract
An underwater mobile body includes: a secondary battery; a
detector that detects a remaining amount of electricity stored in
the secondary battery; a power generation unit that uses natural
energy to generate electricity with which the secondary battery is
charged; and a transition unit that when the remaining amount of
electricity detected by the detector decreases below a
predetermined threshold, causes transition to a charge mode in
which the secondary battery is charged.
Inventors: |
NEMOTO; Yoshihiko;
(Kanagawa, JP) ; KIMURA; Tsutomu; (Kanagawa,
JP) ; BABA; Motofumi; (Kanagawa, JP) ; SATO;
Masahiro; (Kanagawa, JP) ; YAMAUCHI; Akihito;
(Kanagawa, JP) ; TOKUCHI; Kengo; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJI XEROX CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
FUJI XEROX CO., LTD.
Tokyo
JP
|
Family ID: |
61830612 |
Appl. No.: |
15/606041 |
Filed: |
May 26, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60L 2200/32 20130101;
B60L 2240/62 20130101; Y02T 90/121 20130101; Y02T 10/7005 20130101;
Y02T 90/14 20130101; Y02T 10/70 20130101; Y02T 10/7072 20130101;
Y02T 10/72 20130101; B63G 2008/005 20130101; B63G 8/001 20130101;
B60L 53/24 20190201; B63G 2008/008 20130101; Y02T 10/7291 20130101;
Y02T 90/162 20130101; Y02T 90/125 20130101; Y02T 90/16 20130101;
B63G 2008/004 20130101; Y02T 90/12 20130101; H02K 7/1823 20130101;
B60L 53/36 20190201; B63G 8/08 20130101; B63G 2008/002
20130101 |
International
Class: |
B60L 11/18 20060101
B60L011/18; B63G 8/08 20060101 B63G008/08; B63G 8/00 20060101
B63G008/00; H02K 7/18 20060101 H02K007/18 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 6, 2016 |
JP |
2016-198246 |
Claims
1. An underwater mobile body comprising: a secondary battery; a
detector that detects a remaining amount of electricity stored in
the secondary battery; a power generation unit that uses natural
energy to generate electricity with which the secondary battery is
charged; and a transition unit that when the remaining amount of
electricity detected by the detector decreases below a
predetermined threshold, causes transition to a charge mode in
which the secondary battery is charged.
2. The underwater mobile body according to claim 1, wherein the
transition unit that has caused transition to the charge mode
causes the underwater mobile body to move to a target position
determined in surroundings of the underwater mobile body, and then
starts to charge the secondary battery.
3. The underwater mobile body according to claim 2, wherein the
transition unit sets the target position to a fixing target object
present in surroundings of the underwater mobile body, and after
the underwater mobile body is fixed to the fixing target object,
the transition unit starts to charge the secondary battery.
4. The underwater mobile body according to claim 2, wherein after
the underwater mobile body is fixed to a fixing target object
present in surroundings of the underwater mobile body, the
transition unit stops a propulsion unit and starts to charge the
secondary battery.
5. The underwater mobile body according to claim 2, wherein after
stopping propulsion by a propeller as a propulsion unit, the
transition unit uses the propeller as the power generation
unit.
6. The underwater mobile body according to claim 2, wherein the
secondary battery is charged using the power generation unit
dedicated for power generation.
7. The underwater mobile body according to claim 1, wherein when a
plurality of types of the power generation unit are mounted as the
power generation unit, the transition unit estimates a total charge
time of each of the plurality of types of the power generation
unit, and determines a power generation unit used for charging
according to a result of the estimation.
8. The underwater mobile body according to claim 7, wherein the
transition unit estimates the total charge time based on a movement
time taken for movement of the underwater mobile body from a
current position to a target position determined in surroundings of
the underwater drone, and a power generation efficiency according
to a type of the power generation unit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2016-198246 filed Oct.
6, 2016.
BACKGROUND
Technical Field
[0002] The present invention relates to an underwater mobile
body.
SUMMARY
[0003] According to an aspect of the invention, there is provided
an underwater mobile body including: a secondary battery; a
detector that detects a remaining amount of electricity stored in
the secondary battery; a power generation unit that uses natural
energy to generate electricity with which the secondary battery is
charged; and a transition unit that when the remaining amount of
electricity detected by the detector decreases below a
predetermined threshold, causes transition to a charge mode in
which the secondary battery is charged.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Exemplary embodiments of the present invention will be
described in detail based on the following figures, wherein:
[0005] FIG. 1 is a diagram illustrating a configuration example of
an underwater drone according to this exemplary embodiment;
[0006] FIG. 2 is a block diagram illustrating an example of a
functional configuration of a controller according to this
exemplary embodiment;
[0007] FIG. 3 is an illustration for explaining switching between
operation modes of an underwater drone;
[0008] FIG. 4 is a flowchart illustrating an example of processing
steps executed by the controller according to this exemplary
embodiment;
[0009] FIG. 5 is an illustration for explaining an example in the
case where equipment installed underwater is used as a charge
site;
[0010] FIG. 6 is an illustration for explaining an example of an
underwater drone that is equipped with a propeller dedicated for
power generation in addition to a propeller for propulsive
force;
[0011] FIG. 7 is an illustration showing an example in which an
underwater drone clings to a ship for charging a battery;
[0012] FIG. 8 is an illustration for explaining an example in which
an underwater drone is fixed to a buoy floating on a water
surface;
[0013] FIG. 9 is an illustration for explaining an example in which
electric power is generated using sunlight;
[0014] FIG. 10 is a diagram illustrating a configuration example of
an underwater drone equipped with multiple types of power
generators;
[0015] FIG. 11 is an illustration for explaining a use example of
an underwater drone equipped with power generators corresponding to
a power generation system utilizing the force of water current and
a power generation system utilizing the sunlight; and
[0016] FIG. 12 is a flowchart illustrating an example of processing
steps executed by the controller when multiple power generators are
selectively used.
DETAILED DESCRIPTION
[0017] Hereinafter, exemplary embodiments of the present invention
will be described in detail with reference to the accompanying
drawings.
[0018] <Exemplary Embodiment>
<Configuration of Underwater Drone>
[0019] FIG. 1 is a diagram illustrating a configuration example of
an underwater drone 1 according to this exemplary embodiment. The
underwater drone 1 is an example of an underwater mobile body, and
more specifically, is a type of an unmanned underwater mobile body.
The underwater drone 1 may be a remote control type or an
autonomous navigation type. In this exemplary embodiment, an
underwater drone of a remote control type is assumed. However, the
details of control described later may be applied to an underwater
drone of an autonomous navigation type.
[0020] The underwater drone 1 has a controller 10 that controls the
units configuring the underwater drone 1, a communicator 15 that is
used for communication with the outside, an illuminator 16 that
illuminates an operating range, an imaging camera 17 that captures
an image of an operating range, a depth sensor 18 that detects a
depth utilizing a water pressure, a steerer 19 that is used for
changing a movement direction, a propeller 20 that generates
propulsive force, a power generator 21 that generates electric
power internally of the underwater drone 1, and a secondary battery
23 that supplies electric power for operations to each unit.
[0021] In the underwater drone 1 according to this exemplary
embodiment, functional units are connected to a controller 10 which
is an example of a control unit. The functional units including the
controller 10 are basically housed in a housing which adopts a
waterproof structure. Electric power is supplied from the secondary
battery 23 to the functional units including the controller 10. The
secondary battery 23 is an example of a power source.
[0022] The controller 10 is configured by a central processing unit
(CPU) 11, a read only memory (ROM) 12, and a random access memory
(RAM) 13. The ROM 12 stores programs to be executed by the CPU 11.
The CPU 11 reads a program stored in the ROM 12, and executes the
program using the RAM 13 as a work area. The CPU 11 controls the
functional units that configure the underwater drone 1, by the
execution of each program.
[0023] The communicator 15 communicates with the outside
wirelessly. In the case of this exemplary embodiment, a sound wave
communicator that transmits and receives sound waves is used as the
communicator 15. It is to be noted that as the communicator 15, a
radio wave communicator that transmits and receives radio waves or
an optical communicator that transmits and receives light may be
used. It is to be noted that the underwater drone 1 may be equipped
with multiple communicators, and may use the communicators
selectively.
[0024] As the illuminator 16, for instance, a halogen lamp, a white
light emitting diode (LED) or a color LED is used. The imaging
camera 17 may be a camera that captures a still image or a camera
that captures a dynamic image. A captured image is stored in the
RAM 13, for instance.
[0025] The depth sensor 18 converts a detected water pressure to a
depth, and outputs the depth to the controller 10. The accuracy of
measurement of and resolution of the depth depend on the depth
sensor 18. The movement direction is controlled by remote control
or in accordance with a program executed by the controller 10. The
movement direction includes not only a direction in a horizontal
plane, but also a vertical direction (a surfacing direction and a
descending direction). The propeller 20 is configured by, for
instance, a propeller and a motor that rotates the propeller. The
motor has a watertight structure to protect the inside from
rusting. The propeller 20 is an example of a propulsive unit.
[0026] The power generator 21 in this exemplary embodiment also
uses a mechanism of the propeller 20, and causes the
above-described motor with the propeller rotatable by the force of
water current to function as a power generator. In other words, the
propeller 20 in this exemplary embodiment is used for generation of
propulsive force in a normal mode, and is used for electric power
generation in a charge mode.
[0027] A retainer 22 is a mechanism that in the charge mode,
attaches and fixes the underwater drone 1 to a fixing target object
as a target position determined in the surroundings of the
underwater drone 1. The retainer 22 in this exemplary embodiment
includes an anchor, a wire, and a wire wind-up mechanism. The wire
wind-up mechanism is used for winding up the anchor after charging
is completed. However, the anchor may be attached to the body
surface of the underwater drone 1. In this case, the wire and the
wire wind-up mechanism are unnecessary. In the case of this
exemplary embodiment, as the fixing target object, a terrain at the
water bottom, such as sand or a rock is assumed.
[0028] <Functional Configuration of Controller>
[0029] Next, the functional configuration of the controller 10 will
be described. FIG. 2 is a block diagram illustrating an example of
a functional configuration of the controller 10 according to this
exemplary embodiment. The controller 10 has a battery remaining
amount detector 101, and a transition controller 102. The battery
remaining amount detector 101 is an example of the detector, and
the transition controller 102 is an example of the transition
unit.
[0030] The battery remaining amount detector 101 obtains
information (for instance, a temperature, a voltage, or a current)
on the secondary battery 23 from the secondary battery 23, and
detects a remaining amount of electricity stored in the secondary
battery 23 based on the obtained information. The detected
remaining amount is outputted from the battery remaining amount
detector 101 to the transition controller 102.
[0031] The transition controller 102 compares the inputted
remaining amount of electricity with a predetermined threshold Th,
and determines an operation mode based on whether or not the
remaining amount is greater than the predetermined threshold Th.
When the remaining amount is greater than the threshold Th, the
transition controller 102 determines use in the normal mode, and
when the remaining amount is less than or equal to the threshold
Th, the transition controller 102 determines switching to the
charge mode.
[0032] The normal mode is a mode in which an operation based on
remote control or a program is executed. For instance, an operation
for underwater search is executed. In contrast, the charge mode is
a mode in which the secondary battery 23 is charged with the
electricity generated by the power generator 21. In the case of
this exemplary embodiment, the charge mode is configured by a
period of time 1 taken for moving the underwater drone 1 to a
target position determined in the surroundings of the underwater
drone 1, a period of time 2 taken for fixing the underwater drone 1
to a fixing target object as a target position, and a period of
time 3 taken for charging the secondary battery 23.
[0033] In the period of time 1, the transition controller 102
determines that the target position is a terrain at the water
bottom, such as a rock or sand in the surroundings of the
underwater drone 1, and controls the steerer 19 and the propeller
20 so as to move the underwater drone 1 closer to the target
position. In the period of time 2, the transition controller 102
drops the anchor from the underwater drone 1, and hooks the anchor
on a rock or sand. In the period of time 3, the transition
controller 102 instructs the power generator 21 to charge the
secondary battery 23 with generated electricity. In the case of
this exemplary embodiment, the propeller of the propeller 20 is
also used by the power generator 21, and thus power generation is
started by rotation of the propeller by water current. The
electricity generated by the power generator 21 is utilized for
charging the secondary battery 23.
[0034] FIG. 3 is an illustration for explaining switching between
operation modes of the underwater drone 1. In FIG. 3, a symbol 200
indicates the water surface, and a symbol 201 indicates the water
bottom (for instance, a rock or sand). The underwater drone 1 in
action at a position P1 is operating in the normal mode. The
underwater drone 1 operating in the normal mode rotates a propeller
20A to generate propulsive force and moves underwater. When the
remaining amount of the secondary battery 23 decreases below the
threshold Th, the underwater drone 1 starts to move (movement 1)
toward the water bottom 201. When being close to a position P2, the
underwater drone 1 extends a wire 22B from the body and fixes an
anchor 22A to the water bottom 201.
[0035] When intense water current is present along the surface of
the water bottom 201, the propeller 20A of the underwater drone 1
fixed to the water bottom 201 is rotated by the force of the water
current and the motor starts power generation. When the charging of
the secondary battery 23 with the generated electricity is
completed, the underwater drone 1 is moved forward against the
water current to remove the anchor 22A from the he bottom of water,
and the underwater drone 1 is collected by winding up the wire 22B.
Subsequently, the underwater drone 1 returns to the normal mode,
and resumes the underwater operation.
[0036] <Processing Steps Executed by Underwater Drone>
[0037] Next, the processing steps executed by the controller 10 of
the underwater drone 1 according to this exemplary embodiment will
be described. FIG. 4 is a flowchart illustrating an example of
processing steps executed by the controller 10 (transition
controller 102) according to this exemplary embodiment. The
controller 10 repeats the processing of the flowchart illustrated
in FIG. 4.
[0038] First, the transition controller 102 determines whether or
not the battery remaining amount is less than or equal to threshold
Th (step 101). The threshold Th is set in advance according to the
type or the capacity size of the secondary battery 23 used. As long
as a negative result is obtained in step 101 (in other words,
during the normal mode), the transition controller 102 repeats the
determination.
[0039] When an affirmative result is obtained in step 101, the
transition controller 102 sets the operation mode of the underwater
drone 1 to the charge mode (step 102). Subsequently, the transition
controller 102 causes the underwater drone 1 to move to a target
position determined in the surroundings of the underwater drone 1
(step 103). In the case of this exemplary embodiment, the
transition controller 102 causes the underwater drone 1 to move to
sand or a rock present in the surroundings of the underwater drone
1.
[0040] Subsequently, the transition controller 102 determines
whether or not preparation for charging is completed (step 104).
The preparation for charging is completed by fixing the anchor 22A
to the water bottom 201. The transition controller 102 detects that
the underwater drone 1 is fixed to the water bottom 201 by a change
in the external force applied to the wire 22B. As long as a
negative result is obtained in step 104, the determination in step
104 is repeated because the preparation for charging is not
completed.
[0041] When an affirmative result is obtained in step 104, the
transition controller 102 stops the propeller 20 (step 105).
Specifically, energization from the secondary battery 23 to the
motor is stopped. Subsequently, the transition controller 102
separates the shaft of the propeller 20A from the propeller 20, and
couples the shaft to the power generator 21. The power generator 21
starts power generation by the rotation of the propeller 20A due to
water current, and charges the secondary battery 23 with the
generated electricity. The transition controller 102 determines
whether or not the charging is completed (step 106). Completion of
charging is detected by whether or not the predetermined threshold
Th1 is exceeded by the detected remaining amount of the battery. As
long as a negative result is obtained in step 106, the
determination operation of step 106 is repeated because the
charging is not completed.
[0042] When the charging is completed and an affirmative result is
obtained in step 106, the transition controller 102 sets the
operation mode of the underwater drone 1 to the normal mode (step
107). Subsequently, the transition controller 102 returns to step
101, and resumes monitoring of the remaining amount of the
secondary battery 23.
[0043] As described above, the underwater drone 1 according to this
exemplary embodiment is equipped with the power generator 21 that
generates power by the force of water current, and when the
remaining amount of the secondary battery 23 decreases below the
threshold Th, the underwater drone 1 moves to the water bottom 201
present in the surroundings of the underwater drone 1, drops the
anchor 22A, generates electric power by the force of water current,
and charges the secondary battery 23. That is, the underwater drone
1 according to this exemplary embodiment charges the secondary
battery 23 while staying in an operating range, and upon completion
of the charging, resumes the operation.
[0044] In other words, since the underwater drone 1 is moved to the
water bottom 201 present in the surroundings of the underwater
drone 1 and the secondary battery 23 is charged in this exemplary
embodiment, it is unnecessary to move the underwater drone 1
precisely to a specific position where a power generation device is
provided. Moreover, when the object of operation is underwater
search, or construction, maintenance, or inspection of underwater
equipment, the water bottom 201 is often present near the operating
range, and thus a movement time before charging is started tends to
be short. Also, even when the weather on the water surface is not
suitable to wind power generation or solar power generation, the
underwater drone 1 can charge the secondary battery 23 underwater,
and is not affected by the weather. For this reason, the underwater
operation time of the underwater drone 1 is stably extended.
[0045] <Other Exemplary Embodiments>
First Modification
[0046] Although the anchor 22A is dropped to the water bottom 201
such as a rock or sand, and the secondary battery 23 of the
underwater drone 1 is charged in the above-described exemplary
embodiment, the secondary battery 23 may be charged with the
underwater drone 1 fixed to equipment installed underwater. FIG. 5
is an illustration for explaining an example in the case where
equipment 300 installed at the water bottom 201 is used as the
target position to be used for charging. The equipment 300 is
provided with a fastener 301 (for instance, U-shaped metal
fittings) 22. In the case of the example of FIG. 5, the underwater
drone 1 is fixed so that a hook 22C attached to the leading end of
the wire 22B is hooked on the fastener 301.
[0047] It is to be noted that in the example of FIG. 5, the hook
22C of the underwater drone 1 is hooked on the U-shaped metal
fittings provided in the equipment 300. However, a configuration
may be adopted in which the equipment 300 is provided with a wire
or a hook and the U-shaped metal fittings are provided in the
underwater drone 1.
[0048] Second Modification
[0049] Although the propeller 20A partially configuring the
propeller 20 is also used as a propeller for power generation in
the above-described exemplary embodiment, the propeller for power
generation may be prepared separately from the propeller 20A for
propulsive force. FIG. 6 is an illustration for explaining an
example of the underwater drone 1 that is equipped with the
propeller 21A dedicated for power generation in addition to the
propeller 20A for propulsive force. Also in the case of FIG. 6, the
underwater drone 1 in the charge mode is fixed to the equipment 300
provided on the water bottom 201.
[0050] A power generator (not illustrated) is mounted on the shaft
of the propeller 21A, and the power generator generates electric
power by rotation of the propeller 21A due to water current. Here
the propeller 21A and the power generator are each an example of
the power generator. The generated electricity is supplied to the
secondary battery 23 through a cable 21B. It is to be noted that in
the normal mode, the propeller 21A, the power generator, and the
cable 21B are stored in the underwater drone 1.
[0051] Third Modification
[0052] Although the underwater drone 1 moves to the water bottom
201, and charges the secondary battery 23 in the above-described
exemplary embodiment, the underwater drone 1 may cling to a mobile
object such as a ship, an underwater creature, or a driftwood which
are moving in the surroundings of the underwater drone 1, and may
charge the secondary battery 23. The mobile object here is an
example of the fixing target object. FIG. 7 is an illustration
showing an example in which the underwater drone 1 clings to a ship
400 for charging the battery. In the case of this example, the
underwater drone 1 clings to the bottom of the ship 400 by a sucker
22D which is an example of a fixing unit. In this case, the
propeller 20A is rotated by the water current generated by the
movement of the ship 400, and electric power is generated. Adoption
of this mechanism allows the secondary battery 23 to be charged
even in a water area with few water currents. It is to be noted
that the sucker 22D is not likely to damage the outer skin of an
underwater creature.
[0053] In the example of FIG. 7, the sucker 22D is used as an
example of a retaining unit. However, the underwater drone 1 may be
fixed to another mobile object using a fastener and a hook as
described in the above-described modification. A mobile object as
the fixing target object is discovered, for instance, by processing
a captured image by the transition controller 102. In the case of
this example, the transition controller 102 may determine that the
discovered mobile object is a fixing target object based on whether
or not the mobile object satisfies predetermined conditions. For
instance, a size or a type is used for the predetermined
conditions.
[0054] Fourth Modification
[0055] Although the water bottom 201, the equipment 300, and the
ship 400 have been presented as examples of the fixing target
object in the above-described exemplary embodiment, a buoy may be
used as the fixing target object. FIG. 8 is an illustration for
explaining an example in which the underwater drone 1 is fixed to a
buoy 500 floating on a water surface 200. In the example of FIG. 8,
the underwater drone 1 is fixed so that the hook 22C provided at
the leading end of the underwater drone 1 is hooked on the fastener
501 provided in the lower surface of the buoy 500.
[0056] It goes without saying that the buoy 500 and the underwater
drone 1 may be fixed together by another technique. For instance, a
hook-shaped fastener may be provided in the buoy 500.
Alternatively, for instance, the buoy 500 and the underwater drone
1 may be fixed together using a sucker. In the example of FIG. 8,
the underwater drone 1 is fixed to the buoy 500 floating on the
water surface 200. However, the underwater drone 1 may be fixed to
a buoy that floats underwater (including the water bottom).
[0057] Fifth Modification
[0058] Although electric power is generated using the water current
in the above-described exemplary embodiment, electric power may be
generated using another natural energy. FIG. 9 is an illustration
for explaining an example in which electric power is generated
using the sunlight. In the example of FIG. 9, the hook 22C of the
underwater drone 1 is attached to the fastener 501 of the buoy 500
floating on the water surface 200. The hook 22C is connected to the
underwater drone 1 via the wire 22B.
[0059] After completion of the attachment, the underwater drone 1
stops the propeller 20, and charges the secondary battery 23 with
the electricity generated by a solar panel 21C. The solar panel 21C
may be affixed to the surface of the underwater drone 1, or a
configuration may be adopted in which the solar panel 21C is stored
in the body in the charge mode at least.
[0060] In the example of FIG. 9, the underwater drone 1 in the
charge mode is fixed to the buoy 500 floating on the water surface
200. However, the underwater drone 1 may float on the water surface
200 independently. That is, the underwater drone 1 in the system
that generates power by the sunlight may charge the secondary
battery 23 without being fixed to a floating object such as the
buoy 500.
[0061] Sixth Modification
[0062] Although water current or the sunlight is utilized as
natural energy in the above-described exemplary embodiment and
modifications, wave power may be utilized. For the power generator
21 utilizing wave power, a system called an air turbine type, or a
system called a gyro system may be used.
[0063] Seventh Modification
[0064] In the above-described exemplary embodiment, the case where
the underwater drone 1 is equipped with a single power generator 21
of one type has been described. However, the underwater drone 1 may
be equipped with multiple power generators 21 of one type. Also,
the underwater drone 1 may be equipped with multiple types of the
power generator 21. FIG. 10 is a diagram illustrating a
configuration example of the underwater drone 1 equipped with
multiple types of power generators. The underwater drone 1
illustrated in FIG. 10 is equipped with a power generator 211
(power generator 1) corresponding to a first power generation
system and a power generator 212 (power generator 2) corresponding
to a second power generation system. It goes without saying that
the underwater drone 1 may be equipped with three or more types of
power generators.
[0065] FIG. 11 is an illustration for explaining a use example of
the underwater drone 1 equipped with power generators corresponding
to a power generation system utilizing the force of water current
and a power generation system utilizing the sunlight. As
illustrated, the underwater drone 1 charges the secondary battery
23 with the electric power generated by either one of the
systems.
[0066] As illustrated in FIG. 11, the depth and the position used
for charging are different between the power generation system
utilizing the force of water current and the power generation
system utilizing the sunlight. For this reason, the underwater
drone 1 which has caused transition to the charge mode has to move
to a target position according to the relevant power generation
system. In the example of FIG. 11, the distance (movement 2) of
movement from the operating range to the water surface 200 is
shorter than the distance (movement 1) of movement from the
operating range to the water bottom 201. Also, the power generation
efficiency which affects a charging rate varies with the intensity
of the sunlight and the strength of water current which are used
for power generation, in addition to a power generation system. For
this reason, the total charge time during the period since
transition to the charge mode until the normal mode is resumed is
not determined by the movement distance only.
[0067] Since a shorter total charge time is desired to achieve a
longer operation time, the transition controller 102 in this
example determines a power generation system (type of power
generator) used for charging by the following steps. FIG. 12 is a
flowchart illustrating an example of processing steps executed by
the controller 10 (the transition controller 102) when multiple
power generators are selectively used.
[0068] First, the transition controller 102 performs the processing
in steps 101 and 102 illustrated in FIG. 4, and causes transition
to the charge mode. Subsequently, the transition controller 102
estimates a total charge time 1 taken for charging the battery when
the first power generator (here, the power generator 211) generates
power (step 201). The total charge time is given as the sum of a
time taken for moving (movement time) from the current position to
a target position determined in the surroundings of the underwater
drone 1, and a time taken for charging the secondary battery
23.
[0069] For estimation of a time taken for charging, the transition
controller 102 refers to a power generation efficiency which is
determined according to a power generation system to be used. At
this point, it is desirable to use environmental information (such
as a current speed, the intensity of the sunlight) on the
surroundings of the underwater drone 1, detected by various sensors
to increase the estimation accuracy. Alternatively, environmental
information may be obtained from the outside via communication and
used.
[0070] Subsequently, the transition controller 102 estimates a
total charge time 2 taken for charging the battery when the second
power generator (here, the power generator 212) generates power
(step 202). It is to be noted that estimation processing of the
total charge time of each of two types of power generation systems
may be performed in parallel.
[0071] Subsequently, the transition controller 102 determines a
power generator with a shorter total charge time taken for charging
(step 203). For instance, it is determined that a power generator
corresponding to the solar power generation system is used.
Subsequently, the transition controller 102 performs the processing
in steps 103 to 107 in FIG. 4, and upon completion of the charging,
causes transition to the normal mode and resumes the operation.
[0072] It is to be noted that in the above-described example,
either one of the multiple types of equipped power generation
systems is selectively used. However, electric power may be
generated using both power generation systems depending on a
combination of equipped power generation systems. For instance,
electric power may be generated by wave power while electric power
is generated by the sunlight.
[0073] Eighth Modification
[0074] Although the underwater drone 1 is equipped with the
communicator 15, the illuminator 16, and the imaging camera 17 in
the above description, the functions to be equipped vary with
applications. Also, although the retainer 22 is controlled by the
controller 10 in FIGS. 1 and 10, in the case where the retainer 22
has a structure (for instance, a hook) for which no control is
necessary, control of the retainer 22 by the controller 10 is
unnecessary.
[0075] Although the exemplary embodiments of the invention have
been described so far, the technical scope of the present invention
is not limited to the scope described in the embodiments. It is
apparent from the description of the claims that various
modifications or improvements of the embodiments are also included
in the technical scope of the present invention.
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